The sexual act of sticking two rocks/buttons/drawing black circles onto the buttocks, one on each buttock. Once in place, a carrot is coated in lubricant and shoved into the anus to complete the greasy snowman.

Guy #1: "Yo, tried the greasy snowman with my girlfriend last night."
Guy #2: "Dude, that's disgusting. Did you hurt her with the carrot?"
Guy #1: "We didn't try it on her."